1. Field of the Invention
The present invention relates to a process and apparatus for recovering the constituent components of a sealed type battery. More particularly, the present invention relates to a process and apparatus for safely and efficiently opening a sealed type battery to recover the constituent components thereof.
2. Related Background Art
In recent years, global warming from the so-called greenhouse effect has been predicted due to the increased level of atmospheric CO.sub.2. To prevent this warming phenomenon from further developing, there is a tendency to prohibit the construction of new steam-power generation plants which exhaust a large quantity of CO.sub.2.
Under these circumstances, proposals have been made to institute load leveling in order to effectively utilize power. Load leveling involves the installation of rechargeable batteries at general locations to serve a storage for surplus power unused in the night, known as dump power. The power thus stored is available in the day time when the power demand is increased, leveling the load requirements in terms of power generation.
Separately, there is an increased societal demand for developing a high performance rechargeable battery with a high energy density for an electric vehicle which would not exhaust air polluting substances. There is further increased societal demand for developing a miniature, lightweight, high performance rechargeable battery usable as a power source for portable instruments such as small personal computers, word processors, video cameras, and pocket telephones.
For the batteries including rechargeable batteries for such uses as above mentioned, there have been developed various storage batteries including rechargeable batteries having an enclosed (or sealed) configuration. Specific examples of such a storage battery are a lead-acid battery, nickel-cadmium battery, nickel-metal hydride battery having a high energy density, nickel-zinc battery, rechargeable lithium battery and the like. In order for these storage batteries to have a long battery lifetime or/and to be ensured in terms of safety, there is usually employed a sealing manner with the use of a battery housing. In addition, in order to ensure further safety, these batteries are mostly provided with a safety vent. This safety vent serves to ensure the safety when the inside pressure of the battery housing is incidentally increased, by communicating the inside of the battery housing to the atmosphere outside the battery housing to thereby reduce the increased inside pressure of the battery housing.
Now, the nickel-metal hydride battery is a rechargeable battery in which electrochemical oxidation-reduction reaction of hydrogen ion is used. The nickel-metal hydride battery typically comprises an anode comprising an anode active material layer comprised of a hydrogen storage (absorbing) alloy, a cathode comprising a cathode active material layer comprised of nickel hydroxide (specifically, nickelous hydroxide), and an electrolyte solution. In this battery, when charging is operated, the hydrogen ion of the electrolyte solution at the side of the anode is reduced into hydrogen, followed by entering into the anode active material layer of the anode where the hydrogen is retained therein, and when discharging is operated, the hydrogen retained in the anode active material layer is oxidized into hydrogen ion, followed by incorporating into the electrolyte solution. For the cathode active material layer of the cathode, the constituent nickel oxyhydroxide is oxidized into a nickel oxide when charging is operated, and when discharging is operated, the nickel oxyhydroxide is reduced into the original nickel hydroxide. For the nickel-metal hydride battery, in order for the hydrogen storage alloy of the anode to efficiently retain hydrogen upon operating the charging and also in order to attain a high battery capacity, the components of the battery are usually sealed in a battery housing.
There are known various lithium batteries in which electrochemical oxidation-reduction reactions of lithium ion is used. In these lithium batteries, because lithium is readily reacted with moisture in the atmosphere to cause a decrease in the battery capacity, there are used an electrolyte solution in which a nonaqueous organic or inorganic solvent which is substantially free of moisture is used, and a battery housing capable of sufficiently sealing their components. And the fabrication of these batteries is conducted in an atmosphere which is sufficiently free of moisture.
Specific examples of these lithium batteries include commercially available primary lithium batteries, commercially available so-called lithium ion batteries, and rechargeable lithium metal batteries (which have been put into the research or which are under development). In the primary lithium battery and rechargeable lithium metal batteries, their anodes have an anode active material layer comprising a lithium metal.
In the lithium ion battery, as the anode active material layer, there is used a carbonous material such as graphite capable of intercalating lithium ion into the network planes of the carbonous material when charging is operated, and as the cathode, there is used a transition metal compound capable of intercalating lithium ion into the transition metal compound when discharging is operated.
Incidentally, the foregoing storage batteries including rechargeable batteries enclosed by such battery housing as above described are used in various portable instruments. For these sealed type batteries, to recover them and to recycle their components is essential not only in terms of development of new portable instruments but also in viewpoints that they are expected to be further developed in the future so that they can be used in electric vehicles, load conditioners, power storage, or the like, and also in a viewpoint that the consumption of the batteries is expected to greatly increase in the future.
However, in order to recover the components of these sealed type batteries, it is necessary to firstly open their battery housings. In this case, problems are liable to occur in that upon the opening, the cathode is often contacted with the anode to cause internal shorts between the two electrodes, where the residual electric capacity is suddenly consumed within a short period of time to cause heat generation, resulting in deteriorating the battery components such that they cannot be recycled. Because of this, there cannot be attained a desirable recovery for the battery components.
In this respect, for the sealed type batteries, there is an increased demand for developing a recovering process including an opening process which enables the efficient recovery of their components without being damaged or deteriorated even in the case where their cathode and anode are contacted with each other upon the opening.